AL5802LPL Просмотр технического описания (PDF) - Diodes Incorporated.
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AL5802LPL Datasheet PDF : 11 Pages
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AL5802LPL
Application Information (Continued)
PWM dimming can be achieved by driving the EN Pin. An external open-collector NPN transistor or open-drain N-Channel MOSFET can be used
to drive the EN Pin as shown in Figure 14. Dimming is achieved by turning the LEDs ON and OFF for a portion of a single cycle. The PWM signal
can be provided by a micro-controller or analog circuitry. Figure 15 is a typical response of LED current vs. PWM duty cycle on the EN Pin.
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Figure 14 Application Circuits for LED Driver with PWM Dimming Functionality
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PWM DUTY CYCLE (%)
Figure 15 Typical LED Current Response vs. PWM Duty Cycle for
REXT = 13Ω at 400Hz PWM Frequency
To remove the potential of incorrect connection of the power supply damaging the lamp’s LEDs, many systems use some form of reverse polarity
protection.
One solution for reverse input polarity protection is to simply use a diode with a low VF in-line with the driver/LED combination. The low VF of the
series-connected diode increases the available voltage to the LED stack and dissipates less power. A circuit example is presented in Figure 16
using Diodes Inc. SBR® (Super Barrier Rectifier) technology. An SDM10U45LP (0.1A/45V) is shown, providing exceptionally low VF for its package
size of 1mm x 0.6mm, equivalent to an 0402 chip style package. Other reverse voltage ratings are also available on Diodes’ website such as the
SBR02U100LP (0.2A/100V) or SBR0220LP (0.2A/20V).
Automotive applications commonly use this method for reverse battery protection.
SBR is a registered trademark of Diodes Incorporated
AL5802LPL
Document number: DS38590 Rev. 3 - 2
8 of 11
www.diodes.com
April 2016
© Diodes Incorporated
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